A conventional binocular includes two indispensable means, that is, a focus adjusting wheel and a zoom adjusting wheel or lever. The focus adjustment is made by rotating a wheel mounted on a center shaft between two left side and right side housings. When a viewer rotates this focus adjusting wheel by a finger while holding the both housings in both hands, the disadvantage is that a binocular body is apt to be moved due to a certain shaking of either finger or hand. Finally, an object for viewing is out of focusing.
On the other hand, a conventional zoom adjustment is also inconvenient in use. The current normal zoom adjustment is made by rotating a lever projected from an eye lens means. While a viewer is holding a binocular housing by one hand, he or she is obliged to operate the above zoom adjusting lever by the other hand. Accordingly, it is unavoidable to prevent a certain shaking of a binocular body. In order to overcome the foregoing disadvantages of the above conventional technique, the present invention has been achieved.